There currently is no mainstream anesthetic agent sensor because existing technologies are too large and heavy to be mounted on a patient's airway. Our aim is to develop the next-generation, compact, high reliability, mid- IR spectrometer which will he able to quickly and unambiguously identify the presence and concentration of a large range of anesthetic gases. The spectrometer would be compact enough to be mounted in the patient's airway, close enough to provide a breath-by-breath response to changing gas composition. Currently, the design and manufacture of a sufficiently compact spectrometer is hindered by the lack of a small, reliable component needed to chop (rapidly turn ON and OFF) the IR (infrared) beam used in the spectrometer. Mid-IR detectors require a chopped light source. Current electro-mechanical choppers are too large, suffer from performance degrading jitter, generate unwanted vibrations, and are less reliable than the electronic components used in spectrometers. We propose to use a compact, inexpensive, electro-optic chopper (non-mechanical, no moving parts) using ferroelectric liquid crystal technology. In addition to medical applications this spectrometer will also be valuable in spectrometers intended for applications such as environmental monitoring and automobile emissions testing. PROPOSED COMMERCIAL APPLICATIONS: The market for this mainstream anesthetic agent sensing is expected to $21M by the year 2003. The introduction of an inexpensive sensor will lead to anesthetic agent sensing becoming mandatory in all US Operating Rooms.